Jordi Isern Institut de Ciències de l’Espai (CSIC-IEEC) MSc in Economics of Science & Innovation Innovation & Challenges: Nanotechnology & Space (3a) Space Mission

Bibliography: * “Spacecraft mission analysis and design”, J.R. Wertz & W.J. Larson (eds.), Kluwer Academic Publishers * “Spacecraft systems engineering”, P. Fortescue & J. Stark (eds.), J. Wiley & Sons

Space mission analysis # Space missions range widely from communications to planetary exploration, to proposals for space manufacturing or even space burial => NO SINGLE PROCESS CAN COVER ALL THE CONTINGENCIES # Space is expensive. Cost is a fundamental limitation # Analysis & design are iterative. Succesive iterations will usually lead to a more detailed better defined mission concept # The results of this iterations have to be documented in order to guarantee the reproductibility of the process Old ESA joke: 1 tm of documents for each payload kg 1Gb

The Space Mission concept: Mission objectives * The subject(s) Mission design Production and deployment Operations and support Mission end The concept of payload: Combination of hardware and software on the spacecraft that interacts with the subject to accomplish the mission objectives The Space Mission concept: Mission objectives * The subject(s) Mission design Production and deployment Operations and support Mission end The concept of payload: Combination of hardware and software on the spacecraft that interacts with the subject to accomplish the mission objectives

Defining a mission concept What space characteristic makes a space mission desirable or necessary? Global perspective  Earth observation Above the atmosphere  Space observatory Gravity-free environment  Materials processing, etc Exploration of space itself  Solar System exploration Is there a rendez-vous or a strong date demand?(ex. a Halley’s comet mission). Defining a mission concept What space characteristic makes a space mission desirable or necessary? Global perspective  Earth observation Above the atmosphere  Space observatory Gravity-free environment  Materials processing, etc Exploration of space itself  Solar System exploration Is there a rendez-vous or a strong date demand?(ex. a Halley’s comet mission).

Setting top level mission requirements Functional requirements: Performance  primary objective definition, payload size, orbit, pointing. Coverage  orbit, number of satellites, scheduling. Responsiveness  communications, processing, operations. Operational requirements: Duration  altitude, level of redundancy, consumables. Availability  level or redundancy, orbit. Survivability  electronics, orbit. Data distribution  communications. Data content and format  payload, processing, user support. Constraints: Environment  orbit, lifetime. Cost, schedule,... Setting top level mission requirements Functional requirements: Performance  primary objective definition, payload size, orbit, pointing. Coverage  orbit, number of satellites, scheduling. Responsiveness  communications, processing, operations. Operational requirements: Duration  altitude, level of redundancy, consumables. Availability  level or redundancy, orbit. Survivability  electronics, orbit. Data distribution  communications. Data content and format  payload, processing, user support. Constraints: Environment  orbit, lifetime. Cost, schedule,...

Broad Steps in Mission Analysis Step 0 - Mission statement Step 1 - Define objectives Define broad objectives and constraints Estimate quantitative mission needs and requirements Step 2 – Characterize the mission Define alternative mission concepts Define alternative mission architectures Identify system drivers for each alternative Define in detail what the system is and does Step 3 – Evaluate the mission concepts Identify critical requirements for each mission concept Evaluate mission utility Select one or more baseline system designs Step 4 – Define requirements Define system requirements Allocate requirements to each system component Broad Steps in Mission Analysis Step 0 - Mission statement Step 1 - Define objectives Define broad objectives and constraints Estimate quantitative mission needs and requirements Step 2 – Characterize the mission Define alternative mission concepts Define alternative mission architectures Identify system drivers for each alternative Define in detail what the system is and does Step 3 – Evaluate the mission concepts Identify critical requirements for each mission concept Evaluate mission utility Select one or more baseline system designs Step 4 – Define requirements Define system requirements Allocate requirements to each system component

Mission arquitecture

The ECSS (European Cooperation for Space Standardization) standard project phasing Phase 0: Mission Analysis/Needs Identification Phase A: Feasibility Phase B: Preliminary Definition (Project and Product) Phase C: Detailed Definition (Product) Phase D: Production/Ground Qualification Testing Phase E: Utilization Phase F: Disposal

Types of space missions Manned vs. unmanned level of autonomy? By objectives: * Communications * Navigation * Earth observation * Science – Remote sensing » Solar System science » Astronomy » Fundamental physics – In situ science » Solar System exploration » Applied physics » Life sciences » Others (materials science, …) * Others Types of space missions Manned vs. unmanned level of autonomy? By objectives: * Communications * Navigation * Earth observation * Science – Remote sensing » Solar System science » Astronomy » Fundamental physics – In situ science » Solar System exploration » Applied physics » Life sciences » Others (materials science, …) * Others

FUEGO Mission statement FUEGO is a system based on space technology that will allow the early detection and monitoring of forest fires through the acquisition of satellite images with high spatial resolution and high frequency of revisit of the fire scene. The main objective of FUEGO is to contribute decisively to the fight against fires in the Mediterranean forests. FUEGO end users will be the national fire fighting and civil protection services. Data flow and formats must meet the needs of both groups without specialized training and must allow them to respond promptly to changing conditions. FUEGO Mission statement FUEGO is a system based on space technology that will allow the early detection and monitoring of forest fires through the acquisition of satellite images with high spatial resolution and high frequency of revisit of the fire scene. The main objective of FUEGO is to contribute decisively to the fight against fires in the Mediterranean forests. FUEGO end users will be the national fire fighting and civil protection services. Data flow and formats must meet the needs of both groups without specialized training and must allow them to respond promptly to changing conditions.

SIXE Mission statement: The ultimate goal of the MINISAT program was the development and construction of a series of medium size and versatile platforms which could be able to be used in different missions without the need of substantial changes in their structure. After the construction of the first spacecraft of this series, the MINISAT-01 one, the Spanish National Plan for Space Research (PNIE) made a call for proposals to choose a new payload for the next mission. SIXE (Spanish Italian X-Ray Experiment) is the final result of a cooperative effort between a spanish institution, the Institut d’Estudis Espacials de Catalunya (IEEC), and an italian one, the Istituto di Astrofisica Spaziale (IAS). SIXE Mission statement: The ultimate goal of the MINISAT program was the development and construction of a series of medium size and versatile platforms which could be able to be used in different missions without the need of substantial changes in their structure. After the construction of the first spacecraft of this series, the MINISAT-01 one, the Spanish National Plan for Space Research (PNIE) made a call for proposals to choose a new payload for the next mission. SIXE (Spanish Italian X-Ray Experiment) is the final result of a cooperative effort between a spanish institution, the Institut d’Estudis Espacials de Catalunya (IEEC), and an italian one, the Istituto di Astrofisica Spaziale (IAS).

SIXE has been designed to meet the following set of criteria: a) The goal of the experiment is to provide a reliable X-ray observatory able to study frontier topics through high-precision X- ray timing. b) The technical requirements of the experiment are fully compatible with the MINISAT-01 platform and only a few changes are required with respect to the initial design of the spacecraft. c) According to the spirit of a mission based on a small spacecraft the experiment has been designed to fulfill the scientific goals in a short time and with a small economic budget. SIXE has been designed to meet the following set of criteria: a) The goal of the experiment is to provide a reliable X-ray observatory able to study frontier topics through high-precision X- ray timing. b) The technical requirements of the experiment are fully compatible with the MINISAT-01 platform and only a few changes are required with respect to the initial design of the spacecraft. c) According to the spirit of a mission based on a small spacecraft the experiment has been designed to fulfill the scientific goals in a short time and with a small economic budget.

System drivers: Principal mission parameters or characteristics which influence performance (and cost) and which the designer can control. Choose a few alternative designs based on different options for a few system drivers. System drivers: Principal mission parameters or characteristics which influence performance (and cost) and which the designer can control. Choose a few alternative designs based on different options for a few system drivers.

Examples of system drivers

Allocating requirements: Identify all sources of error that affect to the final product (not just from the spacecraft!) Elements frequently budgeted in space mission design: Allocating requirements: Identify all sources of error that affect to the final product (not just from the spacecraft!) Elements frequently budgeted in space mission design:

Payload design: Types of payloads: In situ (ex. collection and analysis of solar wind particles) Remote sensing (uses only e.m. spectrum, so far) * Imaging (imagers, cameras, …) * Intensity measurement (radiometers, polarimeters, scatterometers, …) * Spectral distribution (spectrometers, …) * Topographic mapping (altimeters, …) Issues: optics, electronics, thermal, structures, mechanisms Active or passive sensors? Payload design: Types of payloads: In situ (ex. collection and analysis of solar wind particles) Remote sensing (uses only e.m. spectrum, so far) * Imaging (imagers, cameras, …) * Intensity measurement (radiometers, polarimeters, scatterometers, …) * Spectral distribution (spectrometers, …) * Topographic mapping (altimeters, …) Issues: optics, electronics, thermal, structures, mechanisms Active or passive sensors?

The “ideal” detector: High spatial resolution AND large useful area. Good temporal resolution AND ability to handle large count rates. Good energy resolution AND unit quantum efficiency over large bandwidth. Light in weight AND minimal power consumption. Output stable on timescales of years. Negligibly low internal background. Immune to damage by radiation environment. Require no consumables. No moving parts. Low output data rates.... and simple and cheap to construct (and pretty!!) The “ideal” detector: High spatial resolution AND large useful area. Good temporal resolution AND ability to handle large count rates. Good energy resolution AND unit quantum efficiency over large bandwidth. Light in weight AND minimal power consumption. Output stable on timescales of years. Negligibly low internal background. Immune to damage by radiation environment. Require no consumables. No moving parts. Low output data rates.... and simple and cheap to construct (and pretty!!)

Bus design and payloads requirements: Spacecraft bus provides support to the payload through subsystems: Attitude maintenance Orbit control Power Command Telemetry and data handling Structure and rigidity Thermal control Design the spacecraft to meet payload, orbit, and communications requirements. Orbit affects propulsion, attitude control, thermal design, and power. Environment (radiation,...) affects usable materials, spacecraft lifetime, and electronics. Instruments, sensors, solar arrays, and thermal radiators have pointing and FOV requirements. Bus design and payloads requirements: Spacecraft bus provides support to the payload through subsystems: Attitude maintenance Orbit control Power Command Telemetry and data handling Structure and rigidity Thermal control Design the spacecraft to meet payload, orbit, and communications requirements. Orbit affects propulsion, attitude control, thermal design, and power. Environment (radiation,...) affects usable materials, spacecraft lifetime, and electronics. Instruments, sensors, solar arrays, and thermal radiators have pointing and FOV requirements.

Main requirements and constraints for spacecraft design

Spacecraft configuration drivers

Spacecraft subsystems: Propulsion subsystem Attitude Determination and Control Subsystem (ADCS) * Goal: Pointing of instruments, solar panels, antennas, etc. (common or independent pointings). * Sensors to determine the attitude (solar sensor, star tracker, horizon sensor) * Passive (spinning, interaction with Earth’s magnetic or gravity fields) or active (controllers, actuators, torquers, thrusters) control. * Capabilities depend on the number of appendages to be controlled, control accuracy, speed of response and disturbance environment. Communications subsystem * Goal: Uplink commands and ranging tones, and downlink status telemetry, ranging tones, and payload data. * Design depends on data rate, allowable error rate, communications path length, and RF frequency. On-Board Data Handling (OBDH) subsystem * Integrated on the communications subsystem or with an independent structure (computer, etc.) Spacecraft subsystems: Propulsion subsystem Attitude Determination and Control Subsystem (ADCS) * Goal: Pointing of instruments, solar panels, antennas, etc. (common or independent pointings). * Sensors to determine the attitude (solar sensor, star tracker, horizon sensor) * Passive (spinning, interaction with Earth’s magnetic or gravity fields) or active (controllers, actuators, torquers, thrusters) control. * Capabilities depend on the number of appendages to be controlled, control accuracy, speed of response and disturbance environment. Communications subsystem * Goal: Uplink commands and ranging tones, and downlink status telemetry, ranging tones, and payload data. * Design depends on data rate, allowable error rate, communications path length, and RF frequency. On-Board Data Handling (OBDH) subsystem * Integrated on the communications subsystem or with an independent structure (computer, etc.)

Power subsystem * Components: Solar cells, batteries, power conversion, and distribution equipment. * Design depends on average power needed, power needs during eclipses, peak power consumption. * Performance degrades  establish requirements for BOL and EOL. Thermal control subsystem * Goal: Keep instruments, batteries, … inside the operative or the survival temperature range. * Passive (thermal insulation and coatings to balance power dissipation, absorption from Earth & Sun, and radiation to space) or active (electrical heaters, heat pipes). Structural subsystem Power subsystem * Components: Solar cells, batteries, power conversion, and distribution equipment. * Design depends on average power needed, power needs during eclipses, peak power consumption. * Performance degrades  establish requirements for BOL and EOL. Thermal control subsystem * Goal: Keep instruments, batteries, … inside the operative or the survival temperature range. * Passive (thermal insulation and coatings to balance power dissipation, absorption from Earth & Sun, and radiation to space) or active (electrical heaters, heat pipes). Structural subsystem BOL: beginning of life EOL: End of life